psychology AS revision

Correlation

strengths:

1) allows predications to be made and 2) establish realtionships and display realtionships in a quantifiable way. 3) no manipulation of behaviour so is an ethical method.

weaknesses:

1) cannot establish cause and effect, only show realtionships. 2) there may be extraneous realtionships caused from extraneous variables. 3) correlation seems to only work for linear realtionships. 4) there can be Quantification problems.

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Variables

Extraneous variables turn into confuding variables: other variables in the expierment that could influence the result besides the independent and dependent. you can control these variables and they become controlled variables.

operationalising variables: identify the variables, and state how i will manipluate and measure them.

Matched Pairs design - advantage - group differences/particpant variables are controlled. disadvantages - matching can be diffcult, might miss variables, it is also time consuming.

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SAMPLING

random sampling: best type of sampling method to use. every member of the target population has an equal chance of being selected. random sampling is likely to be very representative. can sometimes be impossible to perform.

opportunity sampling: selecting particpants who are ready and available at the time. this sampling method is very easy, cheap and ensure large samples. produce a biased sample. << cannot generalise. can turn into volunteer sampling.

Volunteer sampling: easy, cheap and ensures large sample. particpants may be more motivated or psychology students so perform differently to normal particpants, so you cannot generalise.

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Ethical Issues

1) informed consent: telling the particpant exactly what is going to happen in the expieriment.

2) Right to withdraw

3) Debriefing: particpants informed of the aims, findings and conclusions. the researcher should take steps to reduce any distress that may have been caused.